Diaphragm mounting for stethoscope



. March 7, 1967 w. IL. HOWELL 3,307,650

. DIAPHRAGM MOUNTING ,FOR STETHOSCOPE Original Filed Feb. 5,

1963 3 2 Sheets-Sheet 2 3,307,650 DIAPHRAGM MOUNTING FOR STETHOSCOPEWilliam L. Howell, Washington, D.C., assignor to Taylor InstrumentCompanies, Rochester, N.Y., a corporation of New York Originalapplication Feb. 5, 1963, Ser. No. 257,361, now Patent No. 3,157,246,dated Nov. 17, 1964. Divided and this application Apr. 15, 1964, Ser.No. 360,803 1 Claim. (Cl. 181-24) This application constitutes adivision of my pending application Serial No. 257,361 filed February 5,1963, now Pat. No. 3,157,246.

This invention relates broadly to the art of auscultation, and in itsmore specific aspects it relates to a stethoscope and the diaphragmmounting thereof whereby the tautness of the diaphragm may be adjustedto vary the frequency response thereof; and the nature and objects ofthe invention will be readily recognized and understood by those skilledin the art to which it relates in the light of the following explanationand detailed description of the accompanying drawings illustrating whatI at present believe to be the preferred embodiment or mechanicalexpressions of my invention from among various other forms,arrangements, combinations and constructions, of which the invention iscapable within the spirit and scope thereof.

My invention has been particularly designed for use with medicalstethoscopes for examining the heart, lungs, etc., and, as inconventional stethoscopes provides a diaphragm, membrane or vibratingdisc which is caused to vibrate by the sounds of the heart or otherorgan and thereby produces sound waves which are carried through tubesto the ears of the examiner.

In the medical field it has now been determined that most soundsproduced by the heart are of low frequency, however, it has also beenestablished that the sounds produced in the case of aortic insufiiciencyand in certain pulmonary disorders are of high frequency.

The behavior of a diaphragm depends upon its thickness, the materialwith which it is made, and such behavior also depends upon the tautnessof the diaphragm.

Efforts have been made to provide diaphragms which will mask the lowfrequency signals while responding to and reproducing the high frequencysignals. Such attenuation is said to be attained by the Bowlesstethoscope which provides a relatively rigid diaphragm of relativelysubstantial thickness to make the high frequency sounds better audibleto the human car.

It is known that the masking of low frequency sounds increasesproportionally to the thickness of the diaphragm.

Prior to my invention, as far as I am aware, all efforts to provide astethoscope which will make high frequency sounds audible have beenbased on diaphragm thickness and materials of which the diaphragm ismade, so that no stethoscope is presently available which is capable ofpicking up sounds of varying frequency so that the normal low frequencysounds and certain high frequency sounds are clearly audible by the useof one instrument, having a single diaphragm. 1

I have discovered that by using a diaphragm of uniform thickness andtensile strength which may be formed of a suitable plastic such asmylar, or shim stock, such as steel, the low frequency and highfrequency sounds may both be audible depending upon the tautness of thediaphragm. The diaphragm may be tightened or loosened to operate at thesame frequency as the sounds being picked up for clear audition thereof.

In implementing my concept I have devised a stethoscope having uniquemeans whereby the tautness of the diaphragm may be varied in order toobtain the aforemfg mun... as ure. I

mentioned highly desirable results. Such'adjusting means are simple tooperate and give to the examining physician a substantially larger scopeof audible sounds than has heretofore been possible with one instrument.

In contra-distinction to the single optimum frequency of a violinstring, multiple optimum frequencies are inherent in a diaphragm, andthe location of such optimum frequencies on the frequency scale may bealtered by a change in the tautness of the diaphragm asprovided by myinvention.

My invention is not only useful with conventional stethoscopes, but isalso useful in demonstrations and the like to large 'or small audienceswhere mechanical diaphragms are used on electronic amplifiers to obtainopti mum volume.

The means which I have developed for adjusting the tautness of thediaphragm or membrane do not add substantially to the cost of theinstrument and are not of a complex nature and have high life expectancyunder normal use conditions.

With the foregoing general objects, features and results in view, aswell as certain others which will be apparent from the followingexplanation, the invention consists in certain novel features in design,construction, mounting and combination of elements, as will be morefully and particularly referred to and specified hereinafter.

. Referring to the accompanying dawings:

FIG. 1 is a vertical sectional view of the microphone head of astethoscope showing the diaphragm assembled and in readiness forclamping to the desired degree of tautness.

FIG. 2 is a view similar to FIG. 1 with the diaphragm in one of itsadjusted stretched positions.

FIG. 3 is a vertical sectional view of a further form of my inventionillustrating the microphone head of a stethoscope with the diaphragmassembled with the head and in readiness for clamping to the desireddegree of tautness.

FIG. 4 is a view similar to FIG. 3 illustrating the diaphragm clampedbetween the pair of stretching rings.

In the accompanying drawings, and particularly FIGS. 1 and 2 thereof, Ihave disclosed a head of a stethoscope as comprising the usual bowlwhich I have designated in its entirety by the numeral 1. This bowl isof generally conical shape having an outer annular flange 3 which isexternally threaded as at 5, and is formed with a tube 7 extending fromthe annular flange 3. As is well understood in this art, the tube 7communicates with a pair of tubes (not shown) the ends of which areadapted for placement in the ears of the examining physicion. The outersurface 9 of the flange 3 provides a plane surface which, as will beexplained hereinafter, functions as a bearing surface in the diaphragmadjusting operation.

I providea clamping ring which is designated in its entirety by thenumeral 11. This clamping ring consists of an annular skirt 13 which isinternally threaded as at 15, and from the outer endof the skirt 13 aninwardly extending flange 17 is provided, the under portion of theflange 17 presenting a plane surface 19. On the opposite orouterisurface, of flange 17. I fixa ring ofplastic; 21- which upstandsfrom the flange and may be caused to adhereto the flange by any suitablemeans, The purpose of this plastic ,annuluswill be. explainedhereinafter.

The diaphragm 23 comprises a disc of uniform thickness throughout andhaving tensibility so that the tautness of the diaphragm maybe varied bythe unique adjusting means which I have devised. The diaphragm ormembrane 23 is preferably formed of a plastic such as Mylar, or it maybe formed of steel shim stock and is preferably of a diameter less thanthe diameter of the skirt 13 of the clamping member or ring 11;

The diaphragm 23 is held in assembled position and is stretched to varyits degree of tautness by means of a washer 25 and a cam ring 27, thewasher and ring preferably being of equal diameters and formed of anysuitable material, such as metal, having a degree of resilience. Thewasher 25 is formed with plane or flat upper and lower surfaces 29 anddepending from the washer adjacent to but inwardly spaced from theperiphery thereof is a continuous tooth 31. As will be apparent fromconsideration of the drawings, the washer is preferably of lessthickness than the cam ring, while they are desirably of the same width,and the diameter of the diaphragm is preferably greater than the CD. ofthe washer and the cam ring.

The cam ring 27 is formed in its upper surface with a continuous notch33 which is aligned with the continuous tooth 31 on washer 25 so that,as will be explained, when the washer and cam ring are brought intoengagement the tooth will be received in the notch.

The upper surface 35 of cam ring 27 is plane with the exception of thecontinuous notch 33 and the lower surface of cam ring is formed with aninner bearing surface 37 from which extends radially outwardly andupwardly a camming surface 39.

The various components of my device are assembled by placing the camring 27 on the upper surface 9 of the flange 3 of the bowl 1 with theinner bearing surface 37 of the cam ring resting on and supported by theupper surface of the flange. The diaphragm 23' may then be positioned onthe cam ring, and the diaphragm may, if desired, be formed with acontinuous downwardly depending notch forming a tooth 41 therein whichwill seat in notch 33 formed in the cam ring. The washer 25 is thenlaced on the diaphragm and the cam ring with the continuous toothreceived in the notches in the diaphragm and the cam ring. The clampingring 11 is then threaded on flange 3 of the bowl until flange 17 engagesthe top surface of the washer to clamp the diaphragm between the washerand the cam ring. It will be understood that the diaphragm will besecurely locked or clamped in place because of the continuous tooth andthe notches on the washer and cam ring, respectively.

With the components assembled, as described, the tautness or stretch ofthe diaphragm may be increased by screwing the clamping ring furtheronto the flange of the bowl. When this is done, the flange 17 whichengages the washer radially outwardly of its transverse center line andin a line also radially outwardly with respect to plane bearing surface37 of the cam ring, downward forces are applied to the washer and thecam ring causing them to rock or cam outwardly onto the inclined cammingsurface 39 of the cam ring, thereby increasing the diametric distancebetween the inner engaging juncture of the washer and cam ring to causestretching or increased tautness of the diaphragm for the audiblepick-up of high frequency sounds.

It will be recognized that due to the construction of my adjusting meansvarious degrees of diaphragm tautness may be attained and the examiningphysician may adjust the instrument with great facility during thecourse of an examination.

The upstanding plastic ring 21 serves as dual function, for it not onlyensures that the diaphragm will not come into contact with the humanbody, but being a relatively poor conductor, it will feel warmer thanwould the metal when the instrument is applied to the human body duringan examination.

In FIGS. 3 and 4 of the drawings I have illustrated a further form of myinvention and have used the same reference numerals as heretofore usedto describe similar parts. 1

As in the previously described form of this invention, the bowl 1 of thestethoscope is externally threaded as at 5 and the diaphragm 23 isformed of the same material and size as the diaphragm disclosed in FIGS.1 and 2. The clam-ping ring 11 is formed with internally threaded skirt13 and with the inwardly directed flange 17' which is of greater widththan the flange 17 previously described. The upstanding annular covering21 is fixed to the flange 17. In this form of my invention I provide apair of cam rings for clamping and stretching the diaphragm. One ofthese cam rings 1 have termed the outer cam ring and have designated itgenerally by numeral 43, while the other cam ring I have termed theinner cam ring and have designated it generally by the reference numeral45. The upper cam ring 43 is formed with a head 47 having a dependingcontinuous tooth 49 formed thereon. Extending inwardly from theperiphery of the head 47 is an upwardly extending cam annulus 51. Theinner cam ring 45 is also formed with a head 53 having a depending camannulus 55 extending inwardly from the periphery thereof.

In this form of my invention it will be apparent that the flange 17 ofthe clamping ring 11 extends inwardly over the cam annulus 51 so thatupon threading the clamping ring onto the threads 5 of the flange 3 ofbowl 1, the flange 17 will engage cam annulus 51 and move the head 47and tooth 49 into clamping engagement with the diaphragm 23 and the head53 of cam annulus 45. The cam annulus 55 will seat on plane surface 37of flange 3 and upon further screwing of clamping ring 11 on the flange3 lateral forces will be brought into play moving the camming ringsradially outwardly to thereby stretch or increase the tautness of thediaphragm 23 to provide for the picking up of sounds of increasingfrequency. In this form of my invention I also use cam rings of springmetal to obtain the desired results.

I claim:

A head assembly for a stethoscope including a bowl, a diaphragm adaptedto be stretched thereacross, and means clampedly engaging said diaphragmand mounting it in operative position, said means including a pair ofrings rockably supported on said bowl and at least one of said ringsbeing a cam ring and said diaphragm being positioned between said rings,and a clamping ring adjustably mounted on said bowl and including aradially inwardly extending flange adapted to engage one of said ringsand exert pressures thereon to lock the diaphragm therebetween, said camring having a cam surface thereon operable to rock said cam ring and theother ring radially outwardly for stretching the diaphragm, and saidflange engaging said one of said rings radially outwardly with respectto the transverse center thereof to cause said rocking of the rings.

References Cited by the Examiner UNITED STATES PATENTS 1,799,162 4/1931* Goldschmidt 179--181 1,857,794 5/1932 Smythe 181-31 FOREIGNPATENTS 24,27 8 1/ 1912 Great Britain. 75,389 9/ 1932 Sweden.

RICHARD B. WILKINSON, Primary Examiner.

LEO SMILOW, STEPHEN TOMSKY, Examiners,

